Installation instruction;
-> unpack the *.zip file.
-> You will get a file called "ArendSteamRailway.000"
-> Add it to the folder where Beta312.000 and Simulator.exe are also located.
-> Start the simulator.
-> Enjoy!

If the file does not get hosted on the main simulator add on download page I could upload it to filehorst.de if Sjoerd is okay with that. I have made good experiences with them for hosting my Trainz content

It probably won't get hosted on this website as it is not a metro route. It was just a new year special idea from me, to recycle an easteregg I had to take out of Rijndam 2020 (so the work would not go to waste).
I am glad you like it. If you want to host it somewhere else, go ahead.